APPARATUS FOR INTRODUCING AND DISTRIBUTING A FLOWABLE ADDITIVE INTO AN EXHAUST GAS FLOW

Abstract

An apparatus for introducing and distributing a flowable additive into an exhaust gas flow comprises an inlet to receive the exhaust gas flow from a first exhaust gas treatment device, an outlet to output the exhaust gas flow to a second exhaust gas treatment device, a flow conducting device to lead the exhaust gas flow from the inlet to the outlet, and an injector opening into the flow conducting device, wherein an at least substantially straight-line main flow direction of the apparatus is defined by the inlet and the outlet. A mixing section of the flow conducting device arranged downstream of the injector extends obliquely or transversely to the main flow direction.

Claims

1. An apparatus for introducing and distributing a flowable additive into an exhaust gas flow, the apparatus comprising: an inlet to receive the exhaust gas flow from a first exhaust gas treatment device, an outlet to output the exhaust gas flow to a second exhaust gas treatment device, a flow conducting device to lead the exhaust gas flow from the inlet to the outlet, and an injector opening into the flow conducting device, wherein an at least substantially straight-line main flow direction of the apparatus is defined by the inlet and the outlet; and wherein a mixing section of the flow conducting device arranged downstream of the injector extends obliquely or transversely to the main flow direction.

2. The apparatus in accordance with claim 1, wherein the inlet and the outlet have respective passage surfaces that extend at least substantially in parallel with one another and/or that at least regionally overlap in the main flow direction.

3. The apparatus in accordance with claim 1, wherein the mixing section extends in an angular range between 30 and 150 with respect to the main flow direction.

4. The apparatus in accordance with claim 1, wherein the flow conducting device has a deflection section arranged upstream of the mixing section for deflecting the exhaust gas flow and/or for generating an eddy of the exhaust gas flow in the mixing section.

5. An apparatus for introducing and distributing a flowable additive into an exhaust gas flow, the apparatus comprising: an inlet to receive the exhaust gas flow from a first exhaust gas treatment device, an outlet to output the exhaust gas flow to a second exhaust gas treatment device, a flow conducting device to lead the exhaust gas flow from the inlet to the outlet, and an injector opening into the flow conducting device, wherein an at least substantially straight-line main flow direction of the apparatus is defined by the inlet and the outlet; wherein a mixing device of the flow conducting device is arranged downstream of the injector, and wherein the flow conducting device defines a first flow path comprising the mixing section for a first part flow of the exhaust gas flow and a separate second flow path for a second part flow of the exhaust gas flow, with the first and second flow paths being arranged in parallel with one another in a technical flow aspect.

6. The apparatus in accordance with claim 5, wherein the injector opens into the first flow path.

7. The apparatus in accordance with claim 5, wherein the second flow path is adapted for a larger part flow than the first flow path.

8. The apparatus in accordance with claim 5, wherein the second flow path comprises a swirl generating section that generates a swirl in the respective part flow during operation of the apparatus due to its shape.

9. The apparatus in accordance with claim 8, wherein the swirl generating section is configured for generating at least one swirl whose swirl axis is arranged obliquely or transversely to the main flow direction.

10. The apparatus in accordance with claim 8, wherein the swirl generating section has at least one curved wall section.

11. The apparatus in accordance with claim 8, wherein the mixing section opens into a deflection chamber that deflects the part flow exiting the mixing section and supplies it to a gas exit passage that is in flow communication with the swirl generating section.

12. The apparatus in accordance with claim 11, wherein the deflection chamber effects an at least substantially U-shaped deflection; and/or wherein the mixing section and the gas exit passage extend at least substantially in opposite directions.

13. The apparatus in accordance with claim 11, wherein the gas exit passage is in flow communication with the swirl generating section at least through an exit opening.

14. The apparatus in accordance with claim 13, wherein a guide element is arranged in the swirl generating section and deflects the exhaust gas exiting through the exit opening in the direction of a wall of the swirl generating section.

15. The apparatus in accordance with claim 14, wherein the guide element has a U-shaped or V-shaped cross-section or a combination thereof.

16. The apparatus in accordance with claim 8, wherein the mixing section is at least sectionally led around the swirl generating section.

17. The apparatus in accordance with claim 8, wherein the swirl generating section has an intake whose intake surface extends at least substantially in parallel with a passage surface of the inlet; and/or wherein the swirl generating section has an egress whose egress surface extends at least substantially obliquely to a passage surface of the outlet.

18. The apparatus in accordance with claim 8, wherein the swirl generating section has an egress that is arranged such that exhaust gas exiting it acts on at least one section of the first flow path.

19. The apparatus in accordance with claim 8, wherein the swirl generating section has an egress that is arranged such that exhaust gas exiting it is deflected by at least 20 before reaching the outlet.

20. An exhaust gas system having: a first exhaust gas treatment device, a second exhaust gas treatment device, and an apparatus for introducing and distributing a flowable additive into an exhaust gas flow led from the first exhaust gas treatment device to the second exhaust gas treatment device, wherein the apparatus for introducing and distributing the flowable additive is arranged between the first and second exhaust gas treatment devices and the apparatus comprises an inlet to receive the exhaust gas flow from a first exhaust gas treatment device, an outlet to output the exhaust gas flow to a second exhaust gas treatment device, a flow conducting device to lead the exhaust gas flow from the inlet to the outlet, and an injector opening into the flow conducting device, wherein an at least substantially straight-line main flow direction of the apparatus is defined by the inlet and the outlet; and wherein a mixing section of the flow conducting device arranged downstream of the injector extends obliquely or transversely to the main flow direction; and/or wherein a mixing device of the flow conducting device is arranged downstream of the injector, and wherein the flow conducting device defines a first flow path comprising the mixing section for a first part flow of the exhaust gas flow and a separate second flow path for a second part flow of the exhaust gas flow, with the first and second flow paths being arranged in parallel with one another in a technical flow aspect.

21. The exhaust gas system in accordance with claim 20, wherein the first exhaust gas treatment device, the second exhaust gas treatment device, and the apparatus for introducing and distributing the flowable additive are integrated in a common, single-piece or multi-piece, housing and/or at least substantially adjoin one another without a step.

22. The exhaust gas system in accordance with claim 21, wherein an egress surface of the first exhaust gas treatment device and an entry surface of the second exhaust gas treatment device extend at least substantially in parallel with one another and/or overlap at least regionally viewed in a straight-line main flow direction.

Description

[0034] The invention will be described in the following by way of example with reference to the schematic (sectional) drawings.

[0035] FIG. 1 shows an internal combustion engine having an exhaust system in accordance with the invention in a simplified side view;

[0036] FIG. 2 shows the arrangement in accordance with FIG. 1 from the rear;

[0037] FIG. 3 shows a flow conducting device of the exhaust system shown in FIG. 1 from above;

[0038] FIG. 4 schematically shows the flow progression in the flow conducting device in accordance with FIG. 3;

[0039] FIG. 5 shows the flow conducting device in accordance with FIG. 3 from the rear;

[0040] FIG. 6 shows the flow conducting device in accordance with FIG. 3 from below;

[0041] FIG. 7 shows the flow conducting device in accordance with FIG. 3 from the front;

[0042] FIG. 8 shows the flow conducting device in accordance with FIG. 3 from the side;

[0043] FIG. 9 shows the flow progression in a swirl generating section of the flow conducting device in accordance with FIG. 3;

[0044] FIG. 10 shows the flow progression in a mixing section of the flow conducting device in accordance with FIG. 3;

[0045] FIG. 11 shows the flow progression in a gas exit passage of the flow conducting device in accordance with FIG. 3; and

[0046] FIG. 12 shows a merging of part flows in the flow conducting device in accordance with FIG. 3.

[0047] The internal combustion engine 11 show in FIGS. 1 and 2 has an exhaust system 13 in accordance with the invention that here comprises a section 15 close to the engine and an undersurface section 17. The section 15 close to the engine has an exhaust gas turbocharger 19, a first exhaust gas treatment device in the form of an oxidation catalyst 20, and a second exhaust gas treatment device in the form of a reduction catalytic converter 21, in particular an SCR catalytic converter. An apparatus 25 in accordance with the invention for introducing and distributing a flowable reductant into an exhaust gas flow 46 is arranged between the oxidation catalyst 20 and the reduction catalytic converter 21.

[0048] As shown, the oxidation catalyst 20, the apparatus 25, and the reduction catalytic converter 21 are arranged at least substantially coaxially to one another. The exit surface 27 of the oxidation catalyst 20 in particular extends at least substantially in parallel with the entry surface 29 of the reduction catalytic converter 21. The apparatus 25 has an inlet 30 and an outlet 31 whose passage surfaces 33, 34 extend at least substantially in parallel with one another and thereby define a straight-line main flow direction 35. The passage surfaces 33, 34 furthermore extend at least substantially in parallel with the exit surface 27 of the oxidation catalyst 20 and with the entry surface 29 of the reduction catalytic converter 21. The passage surfaces 33, 34, the exit surface 27 of the oxidation catalyst 20, and the entry surface 29 of the reduction catalytic converter 31 overlap one another and are preferably at least substantially congruent.

[0049] The oxidation catalyst 20, the reduction catalytic converter 21, and the apparatus 25 are integrated in a common housing 37 and substantially adjoin one another at least without a step. The connection of the housing 37 to the exhaust gas turbocharger 19 takes place via an inlet funnel 39. An outlet funnel 41 connects the housing 37 to the undersurface section 17 of the exhaust system 13.

[0050] The apparatus 25 for introducing and distributing a flowable reductant into the exhaust gas flow 46 comprises a flow conducting device 45 that leads the exhaust gas flow 46 exiting the oxidation catalyst 20 from the inlet 30 to the outlet 31.

[0051] A dividing apparatus 47, preferably composed of sheet metal and recognizable in FIGS. 3 and 4, is located in the region of the inlet 30 and defines two separate flow paths 48, 49 for respective part flows of the exhaust gas flow 46. As can be recognized in the schematic representation of FIG. 4, the flow paths 48, 49 are arranged in parallel with one another in a technical flow aspect. The division of the exhaust gas flow 46 into the two part flows is asymmetrical in the embodiment shown. The first flow path 48, the upper flow path 48 in FIG. 4, is specifically adapted for a considerably smaller part flow than the second flow path 49. An exemplary preferred division amounts to 95% mass flow to 5% mass flow. Other divisions of the mass flows are, however, also conceivable.

[0052] An injector 51 is provided in an entry section 50 of the first flow path 48 and is configured in a generally known manner for spraying a liquid reductant, in particular an aqueous urea solution, into the part flow of the first flow path 48. A mixing section 50 that extends at least substantially transversely to the main flow direction 35 is located downstream of the entry section 50.

[0053] In detail, the design of the flow conducting device 45 can be seen from the representations of FIGS. 3 to 8. It can in particular be seen from FIG. 6 that the mixing section 55 extends once through the total flow conducting device 45. The intake section 50 configured as a deflection section deflects the part flow of the first flow path 48 and generates an eddy thereof. The mixing section 55 opens into a deflection chamber 57.

[0054] The part flow of the second flow path 49 moves from the inlet 30 into a swirl generating section 59 (FIGS. 7 and 8) that has two oppositely disposed and respectively outwardly curved wall sections 60. Due to this design, a double swirl 65 is formed in the swirl generating section 59 during the operation of the internal combustion engine 11, as can be seen in FIG. 9. The respective swirl axes 66 are preferably arranged in parallel with one another and at right angles to the main flow direction 35.

[0055] The swirl generating section 59 has an inlet surface 67 (FIG. 9) that extends substantially in parallel with the passage surface 33 of the intake 30. The swirl generating section 59 furthermore has an outlet surface 69 (FIG. 6) that extends substantially at a right angle to the passage surface 34 of the outlet 31. This means that the part flow of the first flow path 48 is first deflected such that it flows transversely to the main flow direction 35. Exhaust gas exiting the swirl generating section 59 is in turn deflected before reaching the outlet 31 such that it flows in the main flow direction 35.

[0056] The deflection chamber 57 deflects the part flow exiting the mixing section 55 in U shape and supplies it to an elongate gas exit passage 71 (FIGS. 6 to 9) that extends transversely to the main flow direction 35 and is in flow communication with the swirl generating section 59 through a likewise elongate exit opening 75 (FIG. 7). With respect to the flow guidance, the mixing section 55 and the gas exit passage 71 extend at least substantially in opposite directions (FIG. 6).

[0057] A guide element 77 composed of sheet metal and arranged in the swirl generating section 59 can be recognized in FIGS. 7 and 9 and deflects exhaust gas passing through the exit opening 75 in the direction of the curved wall sections and thus supports the formation of the double swirl. The guide element 77 can have a sectionally U-shaped or V-shaped cross-section. It can also be seen from FIG. 9 that a flange 80 is provided in the region of the inlet 30. It is molded to the dividing apparatus 47 here.

[0058] As can be recognized in FIG. 6, the mixing section 55 is guided laterally around the swirl generating section 59 so that it is heated by it in operation. The egress surface 69 of the swirl generating section 59 is furthermore arranged such that the exhaust gas exiting the swirl generating section 59 acts on the entry section 50 from the outside. Fluid deposits are thus countered.

[0059] In FIGS. 10 to 12, the flow progression within the flow conducting device 45 is shown in simplified form, with respective individual components being omitted for illustration. Eddies arise in both the mixing section 55 and in the gas exit passage 71, as is illustrated by wavy lines. An eddy and/or a swirl is/are also formed in the deflection chamber 57.

[0060] The exhaust gas flow 46 exiting the oxidation catalyst 20 during the operation of the internal combustion engine 11 is therefore divided into two part flows of different amounts. The smaller part flow is deflected and moves to the injector 51 that sprays in the liquid reductant. The latter mixes with the part flow and evaporators to a large extent. The smaller part flow as a consequence has a relatively high concentration of reductant. The larger part flow moves into the swirl generating section 59 without the addition of reductant and is likewise deflected. An effective mixing of the already pre-mixed reductant in the main flow takes place on the merging of the two part flows in the region of the double swirl 56. A particularly homogeneous mixture is thus present at the outlet 31 and the substrate of the reduction catalytic converter 21 is subsequently acted on by it.

[0061] Since both part flows are deflected and in addition the smaller part flow is led around the larger part flow in a bypass arrangement, a relatively long mixing distance and a relatively large evaporator surface results despite the compact, substantially coaxial arrangement.

REFERENCE NUMERAL LIST

[0062] 11 internal combustion engine [0063] 13 exhaust gas system [0064] 15 section close to the engine [0065] 17 undersurface section [0066] 19 exhaust gas turbocharger [0067] 20 oxidation catalyst [0068] 21 reduction catalytic converter [0069] 25 apparatus for introducing and distributing a flowable reductant in an exhaust gas flow [0070] 27 exit surface of the oxidation catalyst [0071] 29 entry surface of the reduction catalytic converter [0072] 30 inlet [0073] 31 outlet [0074] 33 passage surface [0075] 34 passage surface [0076] 35 main flow direction [0077] 37 housing [0078] 39 inlet funnel [0079] 40 outlet funnel [0080] 45 flow conducting device [0081] 46 exhaust gas flow [0082] 49 dividing apparatus [0083] 48 first flow path [0084] 49 second flow path [0085] 50 entry section [0086] 51 injector [0087] 55 mixing section [0088] 57 deflection chamber [0089] 59 swirl generating section [0090] 60 curved wall section [0091] 65 double swirl [0092] 66 swirl axis [0093] 67 intake surface of the swirl generating section [0094] 69 egress surface of the swirl generating section [0095] 71 gas exit passage [0096] 75 exit opening [0097] 77 guide element [0098] 80 flange